Warning: We may get medium-geeky here for moment. Adjust your pocket-protectors accordingly.
Apple is using the iPhone to crack their way into the enterprise. No big surprise there. What is surprising, however, is just how Sun Tzu their being about it. How so?
Bottom line, for an end-user, the interface is the app. Sure, we recognize names like Exchange, ActiveSync, even BES, but for most typical users, firing up Outlook or switching on their Blackberry IS their email. They don't see what's going on programmatically behind the scenes, don't care what protocol is hand-shaking and packetizing their data as it zips from server to server in its chaotic relay from sender to receiver. They just see their email, and they just know that it was there when they needed it.
Given that, Apple licensing Exchange ActiveSync becomes more than just interesting. Why? Because they didn't buy Outlook. They're making their own MobileMail app which will seamlessly handle Exchange, but, oh by the way, will also handle MobileMe (the new .Mac refresh already billed as Exchange for the rest of us), as well as the usual Gmail, Yahoo!, etc.
So, for the end user, ActiveSync disappears behind the MobileMail iPhone interface. And if they have a home account, be it MobileMe, Gmail, Yahoo!, or whatever, the differences become less and less apparent (especially as push-like technologies propagate the different services), and in the end, ActiveSync disappears and people just think of their MobileMail app.
Meanwhile, the technologies behind MobileMail, with the advent of Snow Leopard Server, get more interesting, especially with Apple offering open, standards-based protocols like IMAP IDLE, and developing and releasing to the Open Source community similar code like CalDAV for push calendar and now, CardDAV for push contacts.
All of a sudden, a business could run an Exchange-like server without any Microsoft like licensing fees (which anyone who has dealt with them can tell you are money trap unto themselves).
Most interesting of all, if a business had deployed iPhones and they decided to switch from Exchange to Snow Leopard (or any *nix server using the FOSS implementations on their own), their end users may not even notice.
Roughly Drafted has more on Snow Leopard and its possible implications for Exchange/SharePoint users.